Support loading an EC point with affine zero coordinates.

For example it is possible to construct a point with x coordinate of
zero whenenver b has a square root modulo p.

Found during integration with
https://github.com/catenacyber/elliptic-curve-differential-fuzzer

1 files changed, 47 insertions, 8 deletions

diff --git a/src/tests/test_ecc_pointmul.cpp b/src/tests/test_ecc_pointmul.cpp
index 460c43ee5..0e4e18015 100644
--- a/src/tests/test_ecc_pointmul.cpp
+++ b/src/tests/test_ecc_pointmul.cpp
@@ -1,28 +1,29 @@
 /*
-* (C) 2014,2015 Jack Lloyd
+* (C) 2014,2015,2019 Jack Lloyd
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
 
 #include "tests.h"
 
-#if defined(BOTAN_HAS_ECDSA)
-   #include <botan/ecdsa.h>
+#if defined(BOTAN_HAS_ECC_GROUP)
+   #include <botan/ec_group.h>
 #endif
 
 namespace Botan_Tests {
 
 namespace {
 
-#if defined(BOTAN_HAS_ECDSA)
-class ECC_Pointmult_Tests final : public Text_Based_Test
+#if defined(BOTAN_HAS_ECC_GROUP)
+
+class ECC_Basepoint_Mul_Tests final : public Text_Based_Test
    {
    public:
-      ECC_Pointmult_Tests() : Text_Based_Test("pubkey/ecc.vec", "m,X,Y") {}
+      ECC_Basepoint_Mul_Tests() : Text_Based_Test("pubkey/ecc_base_point_mul.vec", "m,X,Y") {}
 
       Test::Result run_one_test(const std::string& group_id, const VarMap& vars) override
          {
-         Test::Result result("ECC Scalarmult " + group_id);
+         Test::Result result("ECC base point multiply " + group_id);
 
          const Botan::BigInt m = vars.get_req_bn("m");
          const Botan::BigInt X = vars.get_req_bn("X");
@@ -49,7 +50,45 @@ class ECC_Pointmult_Tests final : public Text_Based_Test
          }
    };
 
-BOTAN_REGISTER_TEST("ecc_pointmul", ECC_Pointmult_Tests);
+BOTAN_REGISTER_TEST("ecc_basemul", ECC_Basepoint_Mul_Tests);
+
+class ECC_Varpoint_Mul_Tests final : public Text_Based_Test
+   {
+   public:
+      ECC_Varpoint_Mul_Tests() : Text_Based_Test("pubkey/ecc_var_point_mul.vec", "X,Y,k,kX,kY") {}
+
+      Test::Result run_one_test(const std::string& group_id, const VarMap& vars) override
+         {
+         Test::Result result("ECC var point multiply " + group_id);
+
+         const Botan::BigInt X = vars.get_req_bn("X");
+         const Botan::BigInt Y = vars.get_req_bn("Y");
+         const Botan::BigInt k = vars.get_req_bn("k");
+         const Botan::BigInt kX = vars.get_req_bn("kX");
+         const Botan::BigInt kY = vars.get_req_bn("kY");
+
+         Botan::EC_Group group(Botan::OID::from_string(group_id));
+
+         const Botan::PointGFp pt = group.point(X, Y);
+
+         result.confirm("Input point is on the curve", pt.on_the_curve());
+
+         const Botan::PointGFp p1 = pt * k;
+         result.test_eq("p1 affine X", p1.get_affine_x(), kX);
+         result.test_eq("p1 affine Y", p1.get_affine_y(), kY);
+
+         result.confirm("Output point is on the curve", p1.on_the_curve());
+
+         std::vector<Botan::BigInt> ws;
+         const Botan::PointGFp p2 = group.blinded_var_point_multiply(pt, k, Test::rng(), ws);
+         result.test_eq("p2 affine X", p2.get_affine_x(), kX);
+         result.test_eq("p2 affine Y", p2.get_affine_y(), kY);
+
+         return result;
+         }
+   };
+
+BOTAN_REGISTER_TEST("ecc_varmul", ECC_Varpoint_Mul_Tests);
 
 #endif